1. Field of the Invention
The present invention relates to a substrate testing apparatus and a substrate testing method for testing the surface of a semiconductor wafer or the like.
2. Description of the Background Art
Hitherto, in order to carry out the testing of the surface of a semiconductor wafer such as a silicon wafer at plural locations collectively and efficiently, there has been a method of allowing a probe card 26 to abut against a semiconductor wafer 18 from above, as shown in FIG. 11. A substrate testing apparatus based on the prior art is provided with such a probe card 26, where a probing needle 27 is fixed onto the lower surface of probe card 26 with its tip end pointing downwards. On the semiconductor wafer 18 side, the locations against which probing needle 27 is allowed to abut hereafter referred to as xe2x80x9cabutment pointsxe2x80x9d) are inherently defined by formation of pads or wirings on the surface. Plural probing needles 27 are arranged in such a manner as to correspond to the plural abutment points on the semiconductor wafer 18 surface, respectively. In order to carry out simultaneous testing of the entire surface of semiconductor wafer 18, one makes use of a probe card 26 having a size approximately equal to that of semiconductor wafer 18.
The semiconductor wafers are exposed to various temperature environments due to circumstances of the process for producing semiconductor devices. The semiconductor wafers themselves expand or contract depending on the temperature at each time. When the temperature of semiconductor wafer 18 changes to expand or contract semiconductor wafer 18, the positional relationship among the abutment points on the semiconductor wafer side is also enlarged or diminished.
In the case of a substrate testing apparatus where probing needle 27 is fixed to probe card 26, if a semiconductor wafer expands or contracts to change the arrangement of abutment points, the interval between probing needles 27 will not accord with the interval between the abutment points, thereby raising a possibility that the testing cannot be carried out normally. From now on, according as the semiconductor wafers increase in size and individual elements on the semiconductor wafer surface decrease in size, the thermal expansion/contraction will have a larger influence and the aforesaid problem will be more serious.
Thus, an object of the present invention is to provide a substrate testing apparatus and a substrate testing method capable of performing a collective testing over a wide area of the substrate surface even under different temperature environments by adjusting the interval between the probing needles in accordance with the expansion/contraction of the substrate such as a semiconductor wafer.
In order to achieve the aforementioned object, a substrate testing apparatus according to one aspect of the present invention includes a first rail, a second rail that crosses the first rail, and a probe unit disposed to cover an intersection of the first and second rails and being respectively movable along the first and second rails, wherein the probe unit includes a probing needle that is brought into contact with a surface of a substrate subjected to measurement. By adopting this construction, one can suitably change the relative positional relationship of the probing needle by moving the probe unit along the rails. Therefore, a substrate testing apparatus can be provided that can accord with the change of abutment points due to expansion/contraction of the substrate.
Further, in order to achieve the aforementioned object, a substrate testing apparatus according to another aspect of the present invention includes a first rail group made of a plurality of rails disposed in parallel with each other, a second rail group made of a plurality of rails disposed in parallel with each other in a direction that crosses the first rail group, a plurality of probe units disposed to cover respective intersections of the rails included in the first rail group and the rails included in the second rail group and being movable along the rails included in the first rail group and the second rail group, and corresponding interval maintaining means for keeping each rail included in the first rail group at an interval corresponding to an arrangement of locations to be measured on a substrate subjected to measurement, wherein the plurality of probe units each include a probing needle to be brought into contact with a surface of the substrate. By adopting this construction, one can suitably change the relative positional relationship of the probing needles by moving the plurality of probe units all at a time along the rails even if the measurement is to be conducted at plural sites. Therefore, a substrate testing apparatus can be provided that can accord with the change of abutment points due to expansion/contraction of the substrate.
In the above-described invention, the corresponding interval maintaining means preferably maintains the interval after changing the interval every time the arrangement of the locations to be measured changes. By adopting this construction, one can test the substrate without bringing the probing needles into contact with the parts of the substrate subjected to measurement where the probing needles should not be brought into contact. This eliminates the fear of undesirably damaging the substrate with the probing needles.
In the above-described invention, the corresponding interval maintaining means preferably includes equal interval maintaining means for keeping each rail included in the first rail group at an equal interval. By adopting this construction, one can move the plurality of rails while keeping the rails at an equal interval, so that the plurality of probe units mounted on these rails are also moved all at a time while the interval thereof is kept equal, making it possible to appropriately change the relative positional relationship of the probing needles. Therefore, a substrate testing apparatus can be provided that can accord with the change of abutment points due to expansion/contraction of the substrate.
In the above-described invention, the substrate testing apparatus further includes displacement measuring means for measuring a displacement of one or more observation points on the substrate subjected to measurement, and displacement measurement value feedback means for setting the interval of each rail included in the first rail group, as defined by the equal interval maintaining means, in accordance with a displacement measurement value given by the displacement measuring means. By adopting this construction, one can quantitatively sense the amount of expansion/contraction of the substrate subjected to measurement with the use of displacement measuring means, and can change the interval of rails to accord with the arrangement of the abutment points after the expansion/contraction with the use of displacement measurement value feedback means.
In the above-described invention, the substrate testing apparatus further includes temperature measuring means for measuring a temperature, and temperature measurement value feedback means for setting the interval of each rail included in the first rail group, as defined by the equal interval maintaining means, in accordance with a temperature measurement value given by the temperature measuring means. By adopting this construction, one can quantitatively sense the amount of thermal expansion/contraction of the substrate subjected to measurement on the basis of the data retained in advance. When the amount of expansion/contraction is obtained, one can change the interval of rails to accord with the arrangement of the abutment points after the expansion/contraction with the use of temperature measurement value feedback means.
In order to achieve the aforementioned object, a substrate testing method according to the present invention uses a plurality of probe units disposed to cover respective intersections of rails included in a first rail group made of a plurality of rails disposed in parallel with each other and rails included in a second rail group made of a plurality of rails disposed in parallel with each other in a direction that crosses the first rail group, the plurality of probe units being movable along the rails included in the first rail group and the second rail group and each including a probing needle to be brought into contact with a surface of a substrate subjected to measurement, wherein the probing needles are brought into contact with the substrate in a state in which an arrangement of the plurality of probe units is adjusted so that an interval between the probing needles corresponds to an arrangement of locations to be measured on the substrate. By adopting this method, one can test the substrate without bringing the probing needles into contact with the parts of the substrate subjected to measurement where the probing needles should not be brought into contact. This eliminates the fear of undesirably damaging the substrate with the probing needles. Since the interval of the probe units can be freely changed along the rails, one can easily accord with the change in the arrangement of circuit patterns or the like subjected to measurement.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.